Artificial limb construction



Dec. 18, 1951 J. H. F. STEWART 2,578,854

ARTIFICIAL LIMB CONSTRUCTION Filed Oct. 8, 1948 2 SHEETS-SHEET l I INVENTOR.

JOHN H. F. STEWA ATTORN EY D 1951 J. H. F. STEWART 2, 7

ARTIFICIAL LIME CONSTRUCTION Filed Oct. a, 1948 I 2 SHEETS-SHEET 2 INVENTOR.

JOHN H .F.STEWART FIG.6 fi

ATTORNEY Patented Dec. 18, 1951 UNITED STATESPATENT OFFICE ARTIFICIAL LIMB CONSTRUCTION John H. F. Stewart, Mount Clemens, Mich.

Application October 8, 1948, Serial No. 53,435

This invention relates to artificial body members and particularly to an improved artificial leg.

The invention is more particularly concerned with a leg construction in which the structural members are particularly adapted to cooperate with a hydraulic or mechanical unit for controlling the action of the joints and which provides not only a rugged reliable construction, but one which is of pleasing appearance and may be serviced or repaired with ease.

The invention also deals with a leg construc tion which is particularly adapted for quantity production while at the same time permitting of custom fitting by artisans skilled in that work, and permitting the use of conventional methods for such fitting and conventional materials for those parts of the leg which require it.

More particularly, it is an object of the invention to provide an artificial leg having a rigid exterior contour which closely simulates the natural leg contour and permits full free action at the joints while maintaining a continuous smooth exterior surface in all positions to which the joint may be bent. Specifically, it is an object to provide a construction wherein a rigid structure is provided for each of the three leg members having clearance space at the joints to permit joint action, and to provide a flexible elastic covering continuously extending over the three leg members and smoothly bridging the gaps between them at all joint positions.

A further object of the invention is to provide a construction for the intermediate or shin memher which allows adequate room for a mechanical hydraulic or other type of joint controlling unit in a completely concealed position, and which is at the same time readily made accessible for service or replacement. More specifically, it is an object to provide a leg member having a frame designed for handling the necessary loads with the minimum weight and providing adequate space for the control unit together with a rigid contoured tubular covering for concealing the frame and unit, giving proper shape to the leg member, and which may be readily removed for access to the unit.

It is a further object of the invention to provide a leg member having a load bearing frame which is resilient to endwise compressive forces for the purpose of facilitating leg action.

A further object of the invention is to provide a leg construction, particularly one having a joint control unit in which the more expensive parts may be manufactured in large quantities at re- 3 Claims. (01. 3-3) 2 duced cost, and yet which will permit each leg to be individually fitted to the user by the use of conventional methods and materials. More specifically, it is an object to provide a construction comprising a sub-assembly which includes the shin and ankle joints complete, together with the lower portion of the thigh member and the upper portion of the foot member properly contoured to cooperate with the shin member, and which may be later provided with a custom fitted socket and a custom fitted foot, the contours of which may be smoothly paired to the thigh and foot portions. 7

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings: 7

Figure 1 is a side view of an artificial leg embodying a preferred form of the present invention showing the knee bent.

Figure 2 is a view corresponding to Figure 1 showing the knee straight.

Figure 3 is a fragmentary sectional view on line 33 of Figure 1.

Figure 4 is an exploded view of a sub-assembly forming part ofthe leg illustrated in Figure 1.

Figure 5 is a detail view of a control cable coupling.

Figure 6 is a side view partly in section of the leg shown in Figure 1.

Figure 'I is a partial sectional view taken on line T'l of Figure 6.

Figure 8 is a fragmentary sectional view taken on line 8-8 of Figure 6.

Figure 9 is a fragmentary rear view of the lower portion of the thigh member with the knee joint removed.

Referring now to Figure 1 there is shown a leg having a thigh member Ill, a shin member l2. and a foot member M which are articulated by means of a knee joint I 6 and an ankle joint IS. The foot member may also have a toe joint as indicated at 20.

As shown more particularly in Figures 6 and '7, the shin member is provided with a main frame 22 preferably formed of two welded tubular truss members 24 and 26 having pivot journals at their upper and lower ends. The truss members are joined at their upper end by a U-shaped crossbar 28 and are joined at a point below their center by a cross tube 30. Mounted on a pivot at 32 is a hydraulic control unit generally designated 34 having a knee piston rod 36 at its upper end and an ankle piston rod 38 at its lower end. The unit illustrated is of the type disclosed more fully in my Patent 2,478,721, granted August 9, 1949, although it will be understood that other types of control units may be utilized including those which control only the knee.

The foot member i4 is pivotally secured to the lower end of the frame 22 by a pivot pin 40 extending between the upstanding flanges 42 of a foot attaching piece 44. The lattermay also have a pin 46-to receive a connecting rod-48 pivoted to the ankle piston rod 38. The attaching piece 44 is provided with a cylindrical boss 50 and a cylindrical key 52 which may receivevscrews :54 by which the foot member 56 is attached. The foot member carries a cuff :58 :rigidly secured thereto and extending upwardlyto cover-mostof the ankle joint. The cuff 58 serves not only as a covering but also as a form or guide to whic-hzthe foot member 56 may be conformed or faired in smoothly. when the-.latter is manufactured. The cuff .is .preferably a sheet ,-metal stamping of aluminum or magnesium.

Pivotedtotherupperend of-the-frame 22 is a .knee. bracket 6G rhavingfdependirlg :ears 162 and .64. .The former receive a pin 66 forming the mainknee pivot. and the latter'receive a pivot 68 directly. connected to theknee piston rod 36. .The bracket 60 may be secured to a base-plate 10 forming the base of the thigh-socket iii. A reinforcing bracket 'l2 is also preferably provided together'with a depending knee cap-member M rigidly secured to the plate 10. Securely attached .to. theiupper part f. the base plate. 7-0 is ra'tubular socket .16 which may be-custom-fittedto the stump of-the user. .The socket 16 may be recessedas. shown at .18 -in.-Figure--3 toreceive remote control. cables..80 which connect between a manual control assembly 82 secured-torthe-side of -the socket, .and the lower control :cable sections-84 which connect with the control unit 3 5. Suitable separable couplings-86,.asshown in Fig- .ure..5,;are providedatvthe rear of the kneecap to permit disassemblyof the thighrmember .ifl

frQmtheshin-member 12. ,lniorder to facilitate such disassembly, while maintaining apermanent rigid attachment .ofthe socket-16 to. the base plate Ill, the. knee bracket 6!) maybe attached byscrews .88;..and..90. .The former screwsare received in special screw sockets 92, as shown in Figure B, which permanently ...attach -the reinforcing plate 72 to the base plate 10.

.In .order. to provide a pleasing. appearance to the exterior of the leg and to reasonablysimulate the appearance of the natural leg, while-at the same time permitting a full range of bending of the knee .and ankle jointsrcertainspeciaLprovlsionsrare .-.made.as follows: The shin-member i2 is provided with a rigid tubular shell-92-which 1s, shapedingeneral to simulate a natural-shin. Theshell .92 may be formed of sheet metal, plast1c,. or other. similar. light weight rigid materials. Itis.formed preferably -as-a continuous tube .whlchmay he slipped over the frame from the bottom when the foot 56 is removedfrom its attaching piece :42. The shell-92-may besecured to the cross piece 28 byscrews, as illustrated; and also anchored-to the-frame adjacent'the cross tube 30. The upper'front -face of the shell=92 extends upwardly substantially above the knee pivot-6 6 andits upper edge lies forward of'the knee pivot by-substantially the same amount. In other words, as viewed-in Figure 6, the upper edge of the shin'face lies at a pointwhich is on a line about 45 above the horizontal. pass ng the horizontal.

4 through the axis 66. The depending knee cap member M has its front face curved into a convex shape, the curvature of which as viewed in Figure 6 is approximately along a circular are centered on the pivot 66 in the quadrant just below horizontal. The lower edge of the knee cap lies closely adjacent to the shin facing when the knee is straight and at a point which is on a line passing through pivot 66 about below Thus, when the ,knee is bent substantially the tip ofthe knee cap member 14 lies just forward of the upper edge of the 'front shin facing.

The upper rear part of the shell 92 is cut away as indicated at 94 so that the lower rear portion of the thigh socket 16 may be received therein to provided with two vertical recesses 96 which receive the side edges of: the shell 92 adjacent the .opening 9 21. :These recessesmay\be.somewhat i-w-iderthan necessary. to merely receive the shell edges in order to assure freedom from pinching thee-elastic covering later to .be described. The .lower, end of. theshell 92 may be, curved. upwardly -at its front-and rear. portionsv to. permit swinging .of the. ankle joint without interference with the .cuff 58.

This construction of the rigid exterior-parts-of the leg adjacent the joints-provides,=a:minimum of clearance space at these :points. In order to provide a complete continuous smoothcontour-for appearance purposes andto completely :enclose therworking parts and the-joints,mtherthreerrigid members of theleg are-covered with a flexible elastic tubular sheet covering as illustrated in Figures 1 and-2-at,-98. This coveringamaybe of various materials and onesuitable type comprises an elastic surgical stocking of 'kn-it fabric-which is-stretched tautly over the-leg-and-bridges.the clearance spaces atthe joints l-B-andifl. literderto avoid-depressions at the anklerandlon the front part of the knee joint, thiscovering and the surface of therigid members "arechosen to have .a Y low; frictional I coefiicient so :that the covering '98 may-readily slide upon the surface of the members I'0,-I2,-.an'dl-| 4. 'I'his sliding action takes place along a 'zone adjacent --each-.of' the joints while the joints arebending, and permitsthe covering':98 tobe maintained tautto bridgethe-clearance'spa-ces adjacent the jointi and provide :a smooth continuous contour'to -the-leg: as -alwhole. The :covering-98 may if desired, be -,dipped or sprayed "with latex "on-similar: plasticwaterproof material'in order to make the" leg water=and dust tight,-or the 'coveringmaybe formed ofcontinuous-elastic 'film having-elastic characteristics. The interior; surface of the covering-may beprovided with a lubricant such as i a film of grease or'talc.

"In order toifacilitate manufactureof-thetleg and custom :fitting' in widely distributed localities, the leg is'so constructed that the entire-shin section and knee-and ankle-joints may be-manufacturedin subassembly form by, quantity production methods. As shown in'liigure4,- such a subassembly may comprise a complete shin section l2, including'all the knee'and ankle joint parts, together with asocket attaching piece comprising the'base plate '10, reinforcing plate 12, and the kneeca 14. At its opposite end the subassembly may be'furnished-with the foot attaching piece 42, screws 54, and the cuff "58. Along with'these maybe furnished the control assembly 8214 3 t? a sogaiedcames-to. such a subassembly may be manufactured in large lots in a few standard shin lengths and calf diameters. It may then be provided with a custom fitted socket and foot made locally in the conventional manner by a custom limb maker. The socket and foot parts are readily fitted to the contour of the attaching pieces furnished with the subassembly by any artisans skilled in this work using conventional materials, methods, and tools. At the same time the provision of the knee cap piece and the ankle cuff provide the necessary contours adjacent the knee and ankle joints to insure proper action of the elastic covering.

The tubular frame 24 is preferably given an outwardly bowed form as shown clearly in Figure 7 and is thereby made somewhat resilient to take up shock and compression in an endwise direction which aids materially to the ease in use of the leg. The frame is also somewhat torsionally resilient about the longitudinal axis of the leg to ease twisting strains between the socket and stump of the user.

Another feature of the present construction resides in the foot attaching piece 42 which is of metal and especially formed so as to provide a reliable attachment to the footpiece 56 which may be made of wood or similar material. By the use of the large cylindrical boss 50 together with the flange at the upper end thereof, a relatively large bearing area between the metal and wooden parts is obtained and this together with the cylindrical key 52 has been found to reliably secure the foot member to its attaching piece without loosening during long periods of use.

It will thus be seen that the present invention provides an improved artificial leg construction which is not only rugged and reliable but pleasing in appearance, easily serviced, and readily adapted tomanufacture and fitting at low cost.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In an artificial leg having a thigh socket member, a shin member and a foot member pivotally connected together, the combination of a load bearing frame connecting the knee and ankle pivots, a pivot actuating and control unit carried by the frame, said frame comprising a pair of side frames secured to each other adjacent the pivots in spaced relation and having oppositely bowed portions resiliently deformable under endwise load whereby the shin member may be elastically compressed a substantial amount by the weight of the user.

2. In an artificial leg having a thigh socket member, a shin member and a foot member pivotally connected together, the combination of a load bearing frame connecting the knee and ankle pivots, a pivot actuating and control unit carried by the frame, said frame comprising a pair of welded tube, truss-like, side frames secured to each other adjacent the pivots in spaced relation and having oppositely bowed portions resiliently deformable under endwise load whereby the shin member may be elastically compressed a substan-- tial amount by the weight of the user.

3. In an artificial leg having a thigh socket member, a shin member and a foot member pivotally connected together, the combination of a load bearing frame connecting the knee and ankle pivots, a pivot actuating and control unit carried by the frame and a tubular shell covering the frame and unit, said frame being elastically com pressible in an endwise direction under the weight of the user, and said shell having its ends spaced from the thigh and foot members to permit such compression.

JOHN H. F. STEWART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 9,232 Drake Aug. 31, 1852 44,644 Monroe Oct. 11, 1864 54,364 Kimball et a1. May 1, 1866 1,376,292 Sauze Apr. 26, 1921 2,073,807 Ronowsky Mar. 16, 1937' 2,336,881 Mortensen Dec. 14, 1943 2,478,721 Stewart Aug. 9, 1949 FOREIGN PATENTS Number Country Date 374,931 Germany May 4, 1923 

